Ink jet printers typically include one or more printheads having ink jets that eject drops of ink to form images on print media. The print media may comprise paper, transparency, and the like, and may be provided as a substantially continuous web of media or as discrete sheets of media. A number of different types of ink are available for use by the printheads of ink jet printers. For example, some ink jet printers are configured to utilize phase change ink for printing. Phase change inks are substantially solid at ambient temperatures, but transition to liquid ink when heated to a suitable melting temperature for the ink. Images may be formed on print media with melted phase change ink using a direct printing process or an indirect printing process. In a direct printing process, the melted phase change ink drops are ejected directly onto the print media. In an indirect print process, the melted phase change ink drops are ejected onto an intermediate imaging member for subsequent transfer to the print media.
In both the direct and indirect printing processes, the drops of melted phase change ink may be fixed to the print media by the application of pressure and/or heat to the ink on the print media. For example, in the indirect printing process, the intermediate imaging member may comprise a rotating drum upon which the drops of ink are deposited for forming the images on the print media. A second roller, also referred to as a transfer or transfix roller, is arranged adjacent to the imaging drum to form a nip through which the print media is fed in timed registration with the ink drops on the imaging drum. As the print media is being fed through the nip, the drops of ink are transferred from the imaging drum to the print media, and the pressure, and in some cases heat, generated in the nip between the imaging drum and the transfix roller spreads the drops out and fixes them to the print media.
In a direct printing process, the printheads of the printer are arranged to deposit ink directly onto the print media. The print media is then guided to a spreading assembly, or spreader, for fixing the ink to the print media. The spreader comprises a pair of rollers with one of the rollers in the pair comprising an image side roller, also referred to as a spreader drum, which contacts the printed side of the print media. The other roller in the pair is arranged adjacent to the spreader drum to form a nip through which the print media is fed. Similar to the direct printing process, as the print media is fed through the nip, the pressure, and in some cases heat, generated in the nip spreads the drops out and fixes them to the print media.
One difficulty faced in fixing ink to print media in both direct and indirect print processes is ink adhering or offsetting to the image side roller as the media is fed through the nip. To prevent ink from adhering or offsetting to the image side drum, a drum maintenance system applies release agent to the surface of the image side roller. The release agent is typically a silicone oil or similar fluid material configured to prevent ink from adhering to the surface of the image side drum. The maintenance system includes a release agent applicator, such as a foam roller, that applies the release agent to the drum surface, and a metering blade that meters the applied release agent to a desired thickness.
The metering blade of the drum maintenance system may also be configured to divert excess release agent from the drum surface to a collection pan, tub, or similar type of structure, so that the diverted release agent may be transported back to the applicator for reuse. To enable the release agent to be diverted from the drum surface by the metering blade, the metering blade in previously known systems are arranged below the drum so that excess release agent, debris, and/or contaminants diverted from the drum by the metering blade may flow down the metering blade body and/or drop into the collection pan. Previously known drum maintenance systems, however, are not capable of diverting and capturing release agent applied to the surface of the drum if there is not space available at the bottom of the drum for the placement of a metering blade.